WASHINGTON (Reuters) – U.S. National Transportation Safety Board (NTSB) chairman Robert Sumwalt said Monday that damage to a fan blade in a Pratt & Whitney engine that crashed into a Boeing 777- United Airlines’ 200 is consistent with metal fatigue, according to a preliminary assessment report.
In a briefing, Sumwalt said it was unclear whether Saturday’s failure of the PW4000 engine with a “loud explosion” four minutes after takeoff coincides with another engine failure on another United flight to Hawaii. in February 2018, attributed to fracture in a fan blade.
The engine that crashed the 26-year-old Boeing Co 777 and threw parts over a Denver suburb was a PW4000 used in less than 10% of the world fleet of 777 wide-body aircraft.
In another incident on Japan Airlines (JAL) 9201.T 777 with PW4000 engine in December 2020, the Transportation Safety Board of Japan reported that it found two damaged fan blades, one with a metal fatigue crack. An investigation is ongoing.
The focus is more on engine maker Pratt & Whitney and analysts expect little financial impact on Boeing, but the PW4000’s problems are a new headache for the aircraft maker as it recovers from the much more serious crisis of the 737 MAX. Boeing’s flagship was landed for nearly two years after two fatal crashes.
The United engine fan blade will be examined on Tuesday after being moved to a Pratt & Whitney lab where it will be examined under the supervision of NTSB researchers.
“What’s important is that we really really understand the facts, circumstances, and conditions around this particular event before we can compare it to any other event,” Sumwalt said.
Boeing recommended that airlines suspend the use of aircraft while the FAA identified an appropriate inspection protocol and Japan imposed a temporary suspension of flights.
The Federal Aviation Administration plans to issue an emergency airworthiness directive soon that will require intensified inspections of the fan blades to detect fatigue.
The FAA in March 2019 following the February 2018 United engine failure attributed to fan blade fatigue ordered inspections every 6,500 cycles. A cycle is a takeoff and landing.
Sumwalt said the United incident was not considered an uncontrolled engine failure as the restraint ring contained parts while flying.
There was minor damage to the aircraft body, but no structural damage occurred, he said.
Sumwalt, NTSB, will examine why the engine fairing was separated from the aircraft and also why there was a fire despite indications that the engine fuel had been extinguished.
Pratt & Whitney, owned by Raytheon Technologies Corp., said Sunday it was coordinating with regulators to review inspection protocols.
Nearly half of the world’s fleet of 128 aircraft operated by airlines such as United, JAL, ANA Holdings, Korean Air and Asiana Airlines had already been landed amid a collapse in travel demand due to the coronavirus pandemic.
Report by David Shepardson in Washington and Jamie Freed in Sydney; additional reports by Tracy Rucinski in Chicago Edited by Kim Coghill and Gerry Doyle